Dr. AIX's POSTS — 22 January 2016


If you pay attention to any of the usual audiophile sites or FB pages, you’ve probably seen the Youtube video by Home Entertainment by D-Tronics [Editor’s NOTE: This is not Home Entertainment, which is a different retailer in Texas] that promotes several different AudioQuest HDMI cables. It purports to demonstrate that different qualities of their cables can improve…even dramatically improve…the fidelity of your music. The 6 minute video is presented by David Ellington, who is apparently a member of the AudioQuest marketing team.

He tries to make the case for three different models of AudioQuest HDMA cables ranging in price from $25 to $200 (for one meter). According to the AQ website they make lots of different HDMI models, including the “Diamond” that will set you back $1000. He talks about long-grain wire vs. wires with lots of strands, about the directionality of cables (apparently they listen to them in both directions and pick the one that “sounds” the best), and the different materials that they use to make the cables (copper or silver).

This marketing video would probably not have caught my eye or made it to several audiophile groups that I belong to except that it includes short excerpts from a song following the discussion of each cable. He starts by describing a “generic” HDMI cable…the baseline…and then plays the tune as it sounds through that cable. Each successive cable type…Pearl, Forest, and Chocolate…is described in glowing terms and then the tune is played.

And I can attest to the fact that each cable sounded better than the last one…even through my desktop computer audio system! The generic cable was dull, lifeless, lacked high-frequencies, and was much quieter than the others. The AudioQuest HDMI cables were much clearer, detailed, full fidelity, and louder. As the the price of the cables increased, so did the fidelity of the playback. Pretty convincing stuff, right?

He was talking up the “fidelity” produced by a short HDMI cable. These are digital cables designed and manufactured to meet a rigid set of standards set out by the people behind the HDMI specification. If the cable meets their specs, then it’s capable of accurately passing the digital ones and zeros from the source to the destination. But in this remarkable video, the fidelity of the sound was improved with each new cable. Somehow the digital information was changed to include higher frequencies, louder amplitudes, and smoother equalization. How is that possible. This goes against everything I know as an engineer.

Well, it turns out it’s not possible…no real surprise. I downloaded the video and extracted the soundtrack to a 96 kHz/24-bit WAV file, which I opened in Adobe Audition to get a peek at the spectra and amplitudes of the music clips. Take a look at the plot that I created from the Adobe tool:


Figure 1 – The spectra of the tune played in the AudioQuest promotional video on YouTube. [Click to enlarge]

I haven’t posted a spectragraph for a number of months so let me briefly describe what the producers of this video did with each music sample. Note the red line on the plot, which shows the spectra of the “baseline” generic cable. It shows a continuous attenuation as the frequencies increase with a sharp corner at about 17500 Hz.

The AudioQuest “Pearl” model starts at the same amplitude at the low frequencies but at around 2000 Hz it doesn’t have the same roll off as the generic cable. In other words, it’s much louder (by as much as 10 dB!) than the baseline or inexpensive HDMI cable. Curiously, it doesn’t have the sharp corner at 17500 Hz. It seems the engineers at AudioQuest have figured out a way to do some advantageous digital signal processing on the data stream during the transmission. Or more likely, they modified the tonal characteristics and equalization during a post production stage.

Each subsequent cable with their attendant increased price, improves on the previous one with the same modification. Of course, the “Chocolate” AudioQuest sounds the best. It was the loudest, brightest, and had the smoothest equalization of any of the less expensive models.

This is fraud. Any company that would produce a sales video full of faked results and then post it on YouTube (or anywhere else) is not deserving our your business. They’re not alone, of course. But this is so blatant and deliberate, that it deserves to be called out. At least Geoff Kaitt of Machina Dynamics admits that he’s a snake oil salesman.

And there’s a representative of AudioQuest on the CTA Audio Board. I get booted from the board because I tell the truth but AudioQuest gets a pass for falsifying their ad. As one of their representative told me in an email exchange, “the truth is bad for commerce” [Editor’s NOTE: The actual quote was, “It’s bad for enterprise”. I went back and checked the email thread.]. So the solution is to cheat.

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About Author


Mark Waldrep, aka Dr. AIX, has been producing and engineering music for over 40 years. He learned electronics as a teenager from his HAM radio father while learning to play the guitar. Mark received the first doctorate in music composition from UCLA in 1986 for a "binaural" electronic music composition. Other advanced degrees include an MS in computer science, an MFA/MA in music, BM in music and a BA in art. As an engineer and producer, Mark has worked on projects for the Rolling Stones, 311, Tool, KISS, Blink 182, Blues Traveler, Britney Spears, the San Francisco Symphony, The Dover Quartet, Willie Nelson, Paul Williams, The Allman Brothers, Bad Company and many more. Dr. Waldrep has been an innovator when it comes to multimedia and music. He created the first enhanced CDs in the 90s, the first DVD-Videos released in the U.S., the first web-connected DVD, the first DVD-Audio title, the first music Blu-ray disc and the first 3D Music Album. Additionally, he launched the first High Definition Music Download site in 2007 called iTrax.com. A frequency speaker at audio events, author of numerous articles, Dr. Waldrep is currently writing a book on the production and reproduction of high-end music called, "High-End Audio: A Practical Guide to Production and Playback". The book should be completed in the fall of 2013.

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